The present invention relates to conveying means in the printing arts industry and, more particularly, it relates to conveyors for the transportation of piles of newspapers.
The invention can be used to the utmost effectiveness for conveying piles of newspapers delivered by a delivery arrangement of a web-fed rotary printing press.
At present, newspapers delivered in a continuous stream by the folder of a web-fed rotary printing press are conveyed by means of a conveyor comprising a driven endless chain having carriages mounted thereof for joint travel therewith. Each carriage, in its turn, has clamps mounted thereon for gripping each newspaper in the stream by its side margins, said clamps being actuated by stationary cams.
This known conveyor provides for the reliable transportation of individual newspapers, however, it cannot be used for conveying piles of newspapers.
Conveyors are presently being developed for the newspaper industry for piles of newspapers, comprising a driven three-dimensional endless chain having mounted thereon carriages for travelling jointly therewith. Each carriage has mounted thereon in a cantilever fashion rods with platforms adapted to support piles of newspapers, with the platforms being retained against rocking by a corresponding retaining means during motion of the chain.
These conveyors ensure the reliable conveyance of piles of newspapers with the platforms being retained against rocking; however, this structure is fit predominantly for conveyors having no portions thereof where the plane of the travel varies. Otherwise, it is necessary to provide at such portions additional means for ensuring the strictly horizontal position of the platforms with the piles thereon, as the latter might fall off the platforms.
The provision of such additional means complicates the structure of the conveyor; furthermore, it puts stricter requirements as to the accuracy of the manufacture of the known conveyors.
In a pending application by the same inventors, a conveyor has been disclosed in detail for piles of newspapers, which incorporate clamps comprising spring-biased fork-shaped flaps mounted on the conveyor chain for alternating rotation for the opening and closing of the flaps at loading and unloading stations of the conveyor.
Since the folds of the newspapers in each pile leaving the web-fed rotary press are rotated through 180.degree. relative to the preceding pile, the flaps with their bent-away prongs in each clamp in the known conveyor are alternatingly inclined toward the folds of the newspapers in the pile being conveyed. The flaps are opened by means of followers fixed directly on the flaps, and engageable by stationary cams positioned at the loading and unloading areas.
Although the above-described conveyor is structurally simple and provides for facilitated loading and unloading of the clamps, as well as for three-dimensional conveying of the piles, this conveyor requires, however, in order to prevent displacement of the piles in the clamps, the necessity to ensure uniform clamping of the piles at several points along their margin, which is a relatively complicated task.
Besides, due to the necessity of alternatingly mounting clamps with flaps having their prongs inclined in opposite directions on the conveyor to conform to the position of the folds in the successive piles, a certain difficulty is encountered when the associated web-fed rotary press is being started. This is explained by the fact that prior to starting the rotary press, it is necessary to match the operation of its delivery with the position of the respective clamps of the conveyor, because when the operation of printing is either halted or completed, the conveyor operates independently of the press. Let us explain this in some more detail. In operation of the conveyor, which is driven indepenently of the web-fed rotary press, a clamp arriving at either the loading or unloading area may have its flaps inclined, e.g. to the right, whereas at the same moment the pile of newspapers leaving the delivery of the rotary press may have the folds facing to the left. Therefore, in order to clamp this particular pile, the conveyor must be halted and a clamp appropriate to this particular pile should be brought to the loading area, which involves a loss of time, and hinders the operation of the printing-conveying complex.
It should be also mentioned that the rotation of the flaps by the interaction of their own followers with stationary cams has been found to require highly accurate manufacturing and accurate positioning of the stationary cams.